Cardiovascular Physiology PDF - Summer 2024

CARDIOVASCULAR PHYSIOLOGY 3. The Wiggers diagram and heart sounds Andre Azevedo, DVM, MSc Assistant Professor of Veterinary Physiology [email protected] Learning objectives for this lecture Describe the Wiggers d...

CARDIOVASCULAR PHYSIOLOGY 3. The Wiggers diagram and heart sounds Andre Azevedo, DVM, MSc Assistant Professor of Veterinary Physiology [email protected] Learning objectives for this lecture Describe the Wiggers diagram and the 6 phases of the cardiac cycle Describe the volume pressure diagram of the cardiac cycle List cardiac sounds and what they represent Describe systolic and diastolic murmurs  The cardiac cycle 2 PHASES OF THE CARDIAC CYCLE: ATRIAL SYSTOLE 1 ISOVOLUMETRIC CONTRACTION 2 VENTRICULAR EJECTION 5 ISOVOLUMETRIC RELAXATION closing 3 RAPID VENTRICULAR FILLING 6DIASTASIS a little is still filling a Pressures in the heart PRESSURE AND VOLUME CHANGE DURING THE CARDIAC CYCLE Heart sounds HEART SOUNDS ARE GENERATED WITH THE CLOSURE OF AV AND SEMILUNAR VALVES  Electrocardiogram (ECG) P WAVE The ECG is a graphical record of electric Atrial depolarization potentials generated by the heart muscle QRS COMPLEX during each cardiac cycle Ventricular depolarization These potentials are detected on the surface of T WAVE the body using electrodes attached to the limbs Ventricular repolarization and chest wall The potentials are amplified by the ECG machine Displayed on a special graph paper in voltage and time Very useful tool to characterize Arrhythmias Conduction Disturbances The Wiggers’ Diagram STANDARD DIAGRAM THAT CORRELATES THE PHASES OF THE CARDIAC CYCLE WITH PRESSURE, VOLUME, ECG AND HEART SOUNDS 88 o (shows left side of the heart) we donothm xy drunkandsend to the body puromy  Wiggers Diagram – atrial systole The atria starts contraction after the atrial depolarization Around the middle of the P wave Causes additional 20% filling of the ventricles Éeveua “a” wave is caused by atrial contraction LA pressure increases about 7-8 mmHg Ventricular pressure and volume increase Because of atrial contraction and blood injection andatrialpressure too  Wiggers Diagram – atrial systole The atria starts contraction after the atrial depolarization Around the middle of the P wave Causes additional 20% filling of the ventricles “a” wave is caused by atrial contraction LA pressure increases about 7-8 mmHg Ventricular pressure and volume increase Because of atrial contraction and blood injection Wiggers Diagram – isovolumetric contraction After atrial contraction, the ventricles will start to contract 1st PHASE OF SYSTOLE: ISOVOLUMIC CONTRACTION LV pressure curve increases Closure of the AV valves (S1) theatial No volume change y decrease pressu diffiff.am Around the middle of the QRS complex QRS = ventricular depolarization Wiggers Diagram – isovolumetric contraction After atrial contraction, the ventricles will start to contract 1st PHASE OF SYSTOLE: ISOVOLUMIC CONTRACTION LV pressure curve increases Closure of the AV valves (S1) No volume change Around the middle of the QRS complex QRS = ventricular depolarization Wiggers Diagram – isovolumetric contraction Atrial c wave occurs when ventricles begin to contract Results from slight backflow of blood into the atria at the onset of ventricular contraction but mainly by the closing of the AV valves because of an increase in ventricular pressure  Wiggers Diagram – ventricular ejection As soon as the pressure is high enough to overcome the pressure inside of the aorta (80 mm Hg) Aortic valve opens and blood is pumped out of the LV 2nd PHASE OF SYSTOLE: EJECTION PHASE Ventricular volume curve decreases Aortic pressure curve increases to about 120 mm Hg (systolic pressure) 80 gift  Wiggers Diagram – ventricular ejection As soon as the pressure is high enough to overcome the pressure inside of the aorta (80 mm Hg) Aortic valve opens and blood is pumped out of the LV 2nd PHASE OF SYSTOLE: EJECTION PHASE Ventricular volume curve decreases Aortic pressure curve increases to about 120 mm Hg (systolic pressure)  Wiggers Diagram – ventricular ejection Atrial v wave occurs in the end of ventricular contraction and beginning of relaxation stead increase results from slow flow of blood into the atria from veins while A-V valves are closed After the isovolumic relaxation, A-V valves open, atrial stored blood flows rapidly into the ventricles and v wave disappears (pressure drop o in the atria) Wiggers Diagram – isovolumetric relaxation Then suddenly the ventricles start to relax (DIASTOLE BEGINS) At the end of the T wave T wave = Ventricular repolarization Ventricular pressure curve decreases Aortic valve closes (S2) When AV and SL valves are closed no change in ventricular volume occur (isovolumetric) 1st phase of ventricular diastole Ivb dub Wiggers Diagram – isovolumetric relaxation Then suddenly the ventricles start to relax (DIASTOLE BEGINS) At the end of the T wave T wave = Ventricular repolarization Ventricular pressure curve decreases Aortic valve closes (S2) When AV and SL valves are closed no change in ventricular volume occur (isovolumetric) 1st phase of ventricular diastole  Wiggers Diagram – diastole When aortic valve closes an INCISURA occurs (dichroic notch) Short period of backward flow of blood Then the aortic pressure decreases slowly throughout the diastole Blood flows continually through the peripheral vessels Before ventricle contract again aortic pressure is around 80 mmHg (diastolic pressure)  Wiggers Diagram – rapid filling When pressure decreases in the ventricle, AV valve opens Blood rapid flows from the atria to the ventricles Ventricular volume curve increases 2nd PHASE of ventricular diastole: RAPID FILLING dread inend  Wiggers Diagram – rapid filling When pressure decreases in the ventricle, AV valve opens Blood rapid flows from the atria to the ventricles Ventricular volume curve increases 2nd PHASE of ventricular diastole: RAPID FILLING  Wiggers Diagram – diastasis In the middle third of the diastole only small amount of blood flows into the ventricles Ventricular volume curve slightly increases 3rd PHASE of ventricular diastole: DIASTASIS persists until the SA node initiate an AP leading to atrial contraction  Wiggers Diagram – diastasis In the middle third of the diastole only small amount of blood flows into the ventricles Ventricular volume curve slightly increases 3rd PHASE of ventricular diastole: DIASTASIS persists until the SA node initiate an AP leading to atrial contraction  Wiggers Diagram – atrial systole (again) In the LAST THIRD OF DIASTOLE (4th phase) the atria contract again, and another cycle begins  Wiggers Diagram – volumes END DIASTOLIC VOLUME (EDV) END SYSTOLIC VOLUME (ESV) STROKE VOLUME (SV = EDV – ESV)  Wiggers Diagram – game WATCH THE VIDEO: https://www.youtube.com/watch?v=KmNHqqrFqG8 AND PLAY THE GAME: https://www.purposegames.com/game/wiggers- diagram-game Wiggers Diagram Volume-pressure Diagram  Volume-pressure Diagram A-B: Period of filling Mitral valve opens due to decrease in ventricular pressure at the end of the systole Left ventricular volume increases due to the flow of blood from the LA into the LV Atria contract in the end increasing volume to 120 ml (end diastolic volume) and Pressure to about 5 -7 mmHg At the end of the diastole the LV contract and mitral valve closes  Volume-pressure Diagram B-C: Isovolumic contraction Left ventricular pressure rises without volume changes until the opening of the aortic valve Pressure inside the ventricle increases to equal the pressure in the aorta (80 mm Hg)  Volume-pressure Diagram C-D: Period of ejection After opening of aortic valve, blood will flow into the aorta Ventricular contraction increases during ejection The volume of the LV decreases uams voh.se at  Volume-pressure Diagram D-A: Isovolumic relaxation Systal At the end of the ejection the aortic valve closes, and LV pressure falls back to diastolic pressure level Diastl There is no change in volume until the mitral valve opens and a new cycle begins With the filling of the ventricle folia Syste Eros Diastole Effdash  Heart sounds The phonocardiogram shows the normal heart sounds during a cardiac cycle S1 or 1st SOUND Closing of A-V valves – LUBB Vibrations created in the blood and cardiac walls S2 or 2nd SOUND Closing of the Semilunar valves – DUB S3 or 3rd SOUND Early diastolic - Rush of the blood into the ventricles 4th during rapid filling S4 or 4th SOUND End diastolic - During atrial systole, flush of blood into a stiff/non-compliant ventricle S3 and S4  large animals and some dogs  Heart sounds The phonocardiogram shows the normal heart sounds during a cardiac cycle S1 or 1st SOUND Closing of A-V valves – LUBB Vibrations created in the blood and cardiac walls S2 or 2nd SOUND Closing of the Semilunar valves – DUB S3 or 3rd SOUND Early diastolic - Rush of the blood into the ventricles during rapid filling S4 or 4th SOUND wise 5 Got End diastolic - During atrial systole, flush of blood into a stiff/non-compliant ventricle S3 and S4  large animals and some dogs  Heart sounds - murmurs Murmurs are abnormal heart sounds caused by turbulent flow through cardiac defects Some are exagerations of cardiac sound Ex: Valve regurgitation or valve stenosis Some are extra heart sounds Ex: Ventricular septal defect or Patent ductus arteriosus Murmurs can occur during systole, during diastole or be a continuous murmur The noise is caused by turbulent blood flow Blood flows in response to pressure difference  Heart sounds - murmurs SYSTOLIC MURMURS Occur during ventricular systole More Common! Blood flows toward the place with lower pressure MITRAL OR TRICUSPID INCOMPETENCE Regurgitation AORTIC OR PULMONIC STENOSIS Sistolic turbulence because the valve does not open enough VENTRICULAR SEPTAL DEFECT Hole or cleft in the interventricular septum PATENT DUCTUS ARTERIOSUS (PDA) Persistence after birth of the opening between aorta and pulmonary artery CONTINUOUS MURMUR – aortic pressure is higher than pulmonary artery during all cardiac cycle  Heart sounds - murmurs DIASTOLIC MURMURS Occur during ventricular diastole Less common Blood flows toward the place with lower pressure TRICUSPID OR MITRAL STENOSIS PULMONIC AND AORTIC INSUFFICIENCY PDA Continuous murmur Heart sounds - murmurs Published Online:8 Jul 2016 https://doi.org/10.12968/coan.2016.21.7.376 Questions?